I hate to admit this, but need some professional advice. A couple years after moving into my house I decided that instead fighting with trying to get grass to grow around several large trees in the backyard that it would be a good idea to ring the trees with topsoil and make flower beds around them. The flower beds are about 1' 1/2' deep at the tree trunk and 3' wide around the trees sloping down into the yard. Buried all of the trunk flare. That was four years ago and I just learned that it was really not the best thing to do for the trees. They seem ok, they're alive anyway. My question is, should I now remove the soil built up around the trees or is it to late, the damage is irreversible and I'm a stupid tree killing homeowner? These are five nice large trees, two pin oaks (2-2 1/2' dia.), two sugar maples (1 1/2' dia.), and a tulip tree (yellow poplar??) about 2 1/2' dia. Any advice on what I can do now to help these trees or what to look for as far as signs of deteriorating health would be greatly appreciated. Thanks
I did a bad thing. Can it be corrected?
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Lumberjack
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I would say gently remove the soil gently down to the original grade and trunk flare. Take and post pictures here.
You say the mounds are only 3' wide? is that diameter or radius? Not a very large bed, I hope that the base of the trunk hasnt decayed too much (hopefully not at all). With a bed that small it wouldnt greatly hamper the uptake of the feeding roots, just increase the deacay at the base of the trunk.
Lets see what the higherups say.
You say the mounds are only 3' wide? is that diameter or radius? Not a very large bed, I hope that the base of the trunk hasnt decayed too much (hopefully not at all). With a bed that small it wouldnt greatly hamper the uptake of the feeding roots, just increase the deacay at the base of the trunk.
Lets see what the higherups say.
The higherups have the lowdownLumberjack said:
This lowerup partly agrees with Lum. Remove it from the trunk down to the flare; you may take that removed dirt and make your ring wider with it.
People who get all excited about the dangers of adding fill often overlook the fact that human-caused erosion from leaf removal etc. leaves the trees higher than what the "natural" grade would be if the natural recycling of material took place. Adding loose fertile fill just replaces what man hath taken away.
I added fill onto the rootzone of my tuliptree for hosta planting; worked out well. Roots grow right into it. the sugar maples I'd be a little more careful on, but I think that filling up to the level of any roots that protrude is usually ok.
Kneejerk Bombas
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A foot deep is quite deep, but the circles are small, so many of the roots are outside the added soil.
The biggest problem is the soil up against the trunk. Gently pull it away along with the as much of the added soil as you can and you should be alright.
A big problem with adding soil over roots, is the oxygen levels drop as you go down in the soil profile. In some soils oxygen gets too low to support healthy roots as shallow as a foot or less, so by adding a foot of fill you have put those roots to deep to survive.
As Guy mentioned, small amounts of fill doesn't much bother roots, they grow up into it and thrive.
When you fill around a trunk, the roots grow up into that soil to the surface and then turn in random directions, often times around the trunk. Then as time passes, those roots grow in diameter and girdle the trunk. Planting depth is a major problem of nursery trees. If these trees were planted, they most likely started out too deep, so while your pulling the added soil away, it become necessary to go even deeper with your excavation. Do a search on girdling roots for more information.
The soil against the trunk can also be a problem in that it prevents the tree from growing in diameter, the soil can girdle the tree, as well as decaying the bark and causing problems that way.
The biggest problem is the soil up against the trunk. Gently pull it away along with the as much of the added soil as you can and you should be alright.
A big problem with adding soil over roots, is the oxygen levels drop as you go down in the soil profile. In some soils oxygen gets too low to support healthy roots as shallow as a foot or less, so by adding a foot of fill you have put those roots to deep to survive.
As Guy mentioned, small amounts of fill doesn't much bother roots, they grow up into it and thrive.
When you fill around a trunk, the roots grow up into that soil to the surface and then turn in random directions, often times around the trunk. Then as time passes, those roots grow in diameter and girdle the trunk. Planting depth is a major problem of nursery trees. If these trees were planted, they most likely started out too deep, so while your pulling the added soil away, it become necessary to go even deeper with your excavation. Do a search on girdling roots for more information.
The soil against the trunk can also be a problem in that it prevents the tree from growing in diameter, the soil can girdle the tree, as well as decaying the bark and causing problems that way.
Lumberjack
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Those are the higher ups I was alluding to.
Thanks Lumberjack, Treeseer, and Mike Maas for the advice. This is exactly the type of info I was looking for, and then some. After looking around this site and reading several posts, I have a lot more respect for trees and those who work in tree care. I've already started to remove some of the fill from one of the pin oaks. The tree bark is of coarse covered in dirt/mud, but does not feel soft or seem to be decaying yet, which I was very happy to see. I plan to remove all the dirt up against the trunk down to the ground level and replace it with a very thin layer of mulch (no volcano mulching) around the trees where the flower beds were at. Also, I've heard that spreading a thin layer of top soil on the lawn, called top dressing, is a good way to improve the soil. Kind of an organic fertilizer. I thought this would be a good use for the removed topsoil that would benifit the lawn and trees. Any thoughts on my plans or other recommendations are welcome. Thanks again for the help!
Topdressing can be a good thing; replaces the organic matter that the leaves would have added if they remained.
When you remove the soil be sure that you get deep enough to Find the Flare. If youhave any doubts take a picture and post it here.
Mr. Maas can you clarify "The soil against the trunk can also be a problem in that it prevents the tree from growing in diameter, the soil can girdle the tree"
I know the soil can invite roots to girdle, but how can soil girdle?
When you remove the soil be sure that you get deep enough to Find the Flare. If youhave any doubts take a picture and post it here.
Mr. Maas can you clarify "The soil against the trunk can also be a problem in that it prevents the tree from growing in diameter, the soil can girdle the tree"
I know the soil can invite roots to girdle, but how can soil girdle?
Kneejerk Bombas
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If you think about how a tree base is designed, it's quite ingenious. There is a flare at the base, which sends the wood out horizontally as soon as it enters the soil. As it expands in circumference it is easy for the root to displace the soil, it can just push it up. This explains, in part, why you see surface roots in clay soils, they expand in diameter and pop right out of the soil.
If the wood is growing straight down into the soil, how much can it expand in diameter, if it is surrounded by rocky, clay soil?
In some of the farm fields here in the dairy state, we encounter trees that have had rocks piled in rows along the edge, one place the farmer will allow a tree to grow. As rocks appear in the field, he takes them to the closest place he they will be out of the way, at the tree line at the edge of the field.
In some cases the tree's trunk suffers from rock girdling and eventual demise. Girdling roots or oxygen depletion aren't a problem, just the inability for the trunk to increase in diameter.
I reckon that a clay soil can compress to a strength that could prevent a tree from growing radially, depending on the soil, depth, and tree. It may be a stretch, but it also may be a contributing factor to the problems a buried tree may face.
If the wood is growing straight down into the soil, how much can it expand in diameter, if it is surrounded by rocky, clay soil?
In some of the farm fields here in the dairy state, we encounter trees that have had rocks piled in rows along the edge, one place the farmer will allow a tree to grow. As rocks appear in the field, he takes them to the closest place he they will be out of the way, at the tree line at the edge of the field.
In some cases the tree's trunk suffers from rock girdling and eventual demise. Girdling roots or oxygen depletion aren't a problem, just the inability for the trunk to increase in diameter.
I reckon that a clay soil can compress to a strength that could prevent a tree from growing radially, depending on the soil, depth, and tree. It may be a stretch, but it also may be a contributing factor to the problems a buried tree may face.
ok I'll buy that; I recall the rockpiles at the bases of bur oaks in WI, and see them damaging other oaks here in NC. Trees don't need any extra challenges on top of what we already throw at them; bad air, water...
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